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Talking about the structural craftability of the motor shaft
- Aug 07, 2018 -

Sufficient strength and rigidity are prerequisites for safe and reliable operation of the motor shaft, especially for large and medium-sized motors, which should be strictly checked or demonstrated according to actual working conditions. However, in addition to this, the motor shaft structure processability must also be taken seriously when designing the motor shaft, which is often overlooked, which seriously affects the machining accuracy and processing efficiency.

The number of steps of the axis should be minimized

The fewer the steps, the easier the processing. Especially when using automatic machine tool processing, the number of steps is small to make tool adjustment more convenient.

The length of the joint between the shaft and the bracket should not be too large.

The matching parts of the shaft and the bracket of the medium and large motors are shown in Fig. 1. If all the diameter d is used, the pressing stroke of the pressing shaft will be the full length L1, the contact area is large, the pressure required is also large, and the contact surface is easily scratched.


After the improved structure, the diameter of the middle section is reduced to d-2, and as a non-mating part, the diameter of the mating portions at both ends differs by 1 mm, and the pressing stroke is shortened to L2, thereby overcoming the above disadvantages. The radial positioning of the mating of the L2 portions at both ends facing the bracket is sufficiently reliable.

In this way, at first glance, increasing the number of steps seems to increase processing difficulties. In fact, such large shafts are not machined on automated machine tools, and the number of steps does not have a major impact on tool requirements. After the diameter of the middle section is reduced, the length of the finished car part (L2 + L2) is shorter than the original value L1, and the quality of the finished car is also relatively easy to guarantee. The joint between the shaft and the bracket can also be made into two structures with a diameter difference of 1 mm, as shown in Fig. 2.


The width of the keyway should be as uniform as possible and placed on the same busbar so that all keyways can be milled out in one setup.

According to the national standard, the width of the shaft end keyway is determined according to the diameter of the shaft extension. In the motor design, the width of the other keyways should be as large as the width of the keyway of the shaft end. Sometimes, due to the versatility of some components (such as slip ring devices, etc.), the keyway on the mating portion allows for a different width than the keyway of the shaft extension.